Scientists led by Dr Gilbert Price from the University of Queensland analyzed carbon isotope ratios present in fossil teeth of Protemnodon sp., Macropus sp., the extinct kangaroo Troposodon sp. and the marsupial herbivore Euryzygoma dunense.

The results suggest that these prehistoric animals occupied specialized dietary niches and did not rely on identical sources of food. For example, the extinct kangaroo ate plants similar to those consumed by present-day kangaroos in temperate and tropical regions, rather than the plants that now grow in this region.

“It is during this time that the Australian fauna first began to take on its modern appearance and distinctiveness, with many modern Australian marsupials, such as the agile wallaby Macropus gracilis, first appearing in Pliocene fossil deposits.”

The findings also suggest that southeastern Queensland hosted a mosaic of tropical forests, wetlands and grasslands during the Pliocene.

“It is vital for us to understand what types of environments Australian megafauna thrived in during the Pliocene. Obtaining detailed environmental records from this time can help us find the drivers of the subsequent extinctions of many of these large marsupials,” added lead author Dr Shaena Montanari from the American Museum of Natural History.